Aortic valve bypass is a proven procedure for relieving critical aortic valve stenosis. This procedure comprises the deployment of a bypass conduit, having a prosthetic valve disposed therein, between the left ventricle and the descending aorta. This approach allows blood to be pumped from the left ventricle into the descending aorta without requiring removal of the dysfunctional native aortic valve. See FIG. 1.
In an aortic valve bypass procedure, the connection of the bypass conduit to the descending aorta is commonly referred to as the “distal anastomosis”, and is currently one of the more difficult and time-consuming elements of an aortic valve bypass procedure.
Currently, in order to effect the distal anastomosis, it is necessary to perform an anterior lateral thoracotomy of approximately six inch length in order to gain sufficient access to the descending aorta. The descending aorta is side-clamped so as to engage, but not occlude, the artery. Then a longitudinal slit is made in the clamped portion of the artery wall, and a graft (e.g., the distal end of the bypass conduit, or an element which is to be secured to the distal end of the bypass conduit), typically 14-20 mm in diameter, is sutured in place, substantially perpendicular to the side wall of the descending aorta, so as to establish the desired fluid connection. Once the perimeter of the graft has been secured to the slit aortic wall, the side clamp can be released and the distal anastomosis is complete.
With respect to the foregoing, it should be appreciated that the thickness of the side wall of the descending aorta can vary considerably from patient to patient. Factors influencing the thickness of the side wall of the descending aorta can include, but are not limited to, the presence of exterior fat and connective tissue, interior calcium deposits, and interior ulcerations. In practice, the thickness of the side wall of the descending aorta can vary from about 1 mm to about 4 mm in thickness. This variation in the thickness of the side wall of the descending aorta is a factor which may need to be taken into account when forming the distal anastomosis.
Aortic valve bypass is not currently a common procedure, at least in part due to the relatively difficult and time-consuming nature of the distal anastomosis. Furthermore, aortic valve bypass cannot currently be considered to be a minimally invasive procedure, due to the need to provide an anterior lateral thoracotomy of approximately 6 inch length. However, reducing the size of the thoracotomy with the current procedure is problematic at best, since reduced access to the descending aorta makes cross-clamping and suturing all the more difficult and time-consuming. Also, when the ribs are spread to create access to the thoracic cavity, the ribs can sometimes fracture, thereby causing additional trauma to the patient.
Consequently, there is a need for an improved method and apparatus for effecting the distal anastomosis in an aortic valve bypass procedure.